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By Geoffrey MohanLOS ANGELES TIMES • Sunday April 21, 2013 10:17 AM

LOS ANGELES — Babies wise up fast. By the time infants are 3 months old, their unfinished brains
are laced with a trillion connections, and the collective weight of all those firing neurons
triples in a year.

But the indecipherable babbling and maladroit wiggling so beloved by parents just leave
scientists in baby labs scratching their heads. What do those little people know, and when do they
know it?

A team of French neuroscientists who compared brain waves of adults and babies has come up with
a tentative answer: At 5 months, infants appear to have the internal architecture in place to
perceive objects in adult-like ways, even though they can’t tell us.

“I think we have a pretty nice answer,” said Sid Kouider of the Ecole Normale Superieure in
Paris, whose findings were published Friday in the journal
Science: “Babies as early as 5 months, and probably earlier, are displaying the same
neural aspects of consciousness as adults.”

The findings hint at an early shift from a largely passive biological process shared with other
animals to the uniquely human ability to ponder ourselves and our surroundings in complex and
abstract ways.

Researchers spent the better part of five years fiddling with fussy babies — at 5, 10 and 15
months — who had to sit still while wearing a cap with 128 electrodes and watching images flicker
before them at eye-blink intervals.

“This was heroic,” said University of California at Los Angeles developmental psychologist Scott
Johnson, who was not involved in the study. “It must have taken them forever.”

Said Kouider: “We had to be very patient.”

Researchers have spent decades observing infants’ eye movements, attempting to delve into such
issues as memory, cognition and perception. But there is a limit to what they can infer.

“Four-month-olds can predict trajectories of objects, but do they have a conscious projection of
a ball? Does she wonder, ‘Where is that thing?’ ” Johnson said. “It’s a question we wrestle
with."

Kouider relied on studies of adult brain waves recorded while subjects were presented with
images that flashed for milliseconds. Some images were recognizable, such as a numeral, while the
rest were indecipherable. The study volunteers were asked if they had “seen” anything.

In adults, the brain processes fleeting images — ones presented for less than 200 milliseconds —
in a way that prevents us from consciously perceiving them. That finding has broadened scientists’
understanding of subliminal suggestion and priming of human behavior.

But when images flash for at least 300 milliseconds — roughly the duration of an eye blink —
brain activity increases exponentially, like a seismometer needle responding to a tremor. That’s
also when adults can report that they consciously perceived the image.

The French team recorded equivalent brain waves in the 80 infants who could sit still while
wearing their electrode caps.